APPAREIL DE COUPURE SENSIBLE A PRESENCE DE FLUIDE SUR POMPE DE RELEVAGE

FLUID SENSITIVE SHUTDOWN FOR WELL PUMP

Abrégé anglais

ABSTRACT OF THE DISCLOSURE
A system for disconnecting an oil well pump driving appar-
atus from a circuit in the absence of a liquid or the like in a
pipeline connected from the pump. A vertical member having a
cavity in communication with the interior of the pipeline has
vertically spaced differential pressure unit (DPU) inlets. The
DPU shuts down the pump motor when there is no liquid in the
pipeline.

Revendications

WHAT IS CLAIMED IS:

1. A fluid sensing system comprising: a unit adapted
to pump oil from a well; means actuable to disable said unit;
a pipeline connected from said unit to carry oil pumped from said
well by said unit; a vertical member sealed to said pipeline,
said member having a cavity in communication with the interior
of said pipeline; a differential pressure unit (DPU) having low
and high pressure inlets in fixed positions relative to said
member and responsive to the respective lower and higher pres-
sures in the interior of said cavity respectively above and
below each other, said DPU having an output device to actuate
said means when the pressure within said high pressure inlet is
the same or different from that in said low pressure inlet;
and apparatus to override said means when it is appropriate to
restart said unit and to fill said pipeline and/or said member.

2. The invention as defined in claim 1, wherein said
unit is electrically operable, said means including a main switch
connected from said unit, said DPU causing said main switch to
open to disable said unit, said apparatus including an auxiliary
switch connected in parallel with said main switch.

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Description

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BACKGROUND OF T~E INVENTION
.
This invention relates to fluid sensing systems, and ~Dre
particularly to apparatus for shutting down a pump in the absence
of a liquid in a pipeline or the like.
In the past, failures to shut down oil well pumps at
times has required high maintenance.
PRIOR ART STATEMEN~
Oil pump shutdown systems were disclosed in U. S. Patents
Nos. 2,550,093; 3,276,380; and 3,297,843 issued April 24, 1951,
October 4, 1966, and January 10, 1967, respectively.
By themselves, but not with oil pump shutdown systems,
differential pressure units are old in the art. See U. S. Patent
No. 2,664,749 issued January 5, 1954.
SUl~MARY OF THE INVENTION
' A fluid sensing system comprising: a unit adapted to
pump oil from a well; means actuable to disable said unit; a
pipeline connected from said unit to carry oil pumped from said
well by said unit; a vertical member sealed to said pipeline,
said member having a cavity in communication with the interior
of said pipeline; a differential pressure unit (DPU) having low
and high pressure inlets in fixed positions relative to said
member and responsive to the respective lower-and higher pres-
sures in the interior of said cavity respectively above and
below each other, said DPU having an output device to actuate
said means when the pressure within said high pressure inlet is
the same or different from that in said low pressure inlet; and
apparatus to override said means when it is appropriate to re-
start said unit and to fill said pipeline and/or said member.



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The above-described and other advantages of the present
invention will be better understood from the following detailed
description when considered in connection with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings which are to ~e regarded as merely
illustrative:
Fig. 1 is a part perspective, part sectional
and part elevational view, and a part schematic diagram of the
system of the present invention; and
Fig. 2 is ~ part perspective view and a part
schematic diagram of electrical switches which control a pump
shown in Fig. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
I5 An oil well pumping unit is illustrated at 10 in Fig. 1.
Unit 10 is substantially, but not necessarily, identical to
that shown in U. S. Patent No. 3,297,843.
An internal combustion engine 11 is provided to drive
unit 10. Any apparatus other than engine 11 may also be pro-

vided to drive unit 10. Pump apparatus at 12 has an outlet con-
duit 13 connected to a body 14 through which oil is pumped to
storage tanks 15 and 16.
Body 14 has a hollow, cylindrical, vertical member 17
bolted at 18 thereto and sealed thereto by an O-ring 19.


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A conventional differential pressure unit (DPU) is pro-
vided at 20 having upper and lower inlets 21 and 22, respectively,
at the respective upper and lower ends of member 17. The in-
teriors of inlets 21 and 22 each contain a fill fluid which is
substantially incompressible and separated from the interior of
member 17 by bellows 29 and 3~, respectively. When the in~erior
of member 17 is nearly full or partly full of oil, DPU 20, which

,
has an output shaft 23 shown in Figs. 1 and 2, rotates a
conductive contact arm 24 into engagement with grounded contact
25. A lead 26 from arm 24 keeps engine 11 running by completing
the distributor circuit thereof.
A manually operable switch 27 can be of the momentary
contact type, if desired.
In Fig. 2, switch means 28 of Fig. 1 is illustrated.
OPERATION
If body 14 and member,17 are empty to a certain~extent
or are totally~empty~, and engine 11 is`not running, enyine 11
will remain shut down because switch 27 will be open and DPU
20 will keep arm 24 and contact 25 out of engagement with each
20 ~ other. That is, the distributor circuit of engine 11 will be
kept open. Arm 24 will not engage contact 25 because member 17
will not fill with oil because pump 12 will not supply oil when
it is not driven by engine 11 and unit 10.


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Should it be desirable to start pump 12, switch 27 may
be held closed until member 17 fills with oil.~ DPU 20 will then
move arm 24 into engagement with contact 25 and the distributor
circuit will thereby be completed. Switch 27 mzy then be opened
and engine 11 will continue to run so long as member 17 is
filled or filled to a certain extent with a liquid. The word
"oil" herein means oil or any liquid or liquid-like mass. The
location of arm 24 on shaft 23 will determine at what oil level
in member 17 that arm 24 will disengage contact 25 and shut down
engine 11, unit 10 and pump 12. Arm 24 may be fixed or adjustable
relative to shaft 23.
Shutdown is useful in protecting engine 11, unit 10 and
pump 12 when oil fails to exit conduit l3 or exits therefrom
intermittently at regular or irregular intervals and~or gas exits
in one or a different one of the same ways. Such a shutdown also
saves energy.